IK Multimedia's Stealth Limiter is one of my favorite master channel limiters. It is very easy to setup and transparent. The mode options are also a welcome addition.
With that said, I tend to use PSP Audioware's Xenon the most on the master channel. However, I would be more than happy with only the Stealth Limiter, if I did not own licenses to other options.
If I need a limiter for a track or buss channel, I lean towards the Brainworx bx_limiter or use the limiter contain within a channel strip plugin.